1. Field of the Invention
This application relates to centrifugal blower wheels such as used in air moving equipment, including furnaces, air conditioners, and HVAC equipment in general. In particular, the present application is directed to disc type centrifugal blower wheels having a center disc and a plurality of blades, each blade having a notch frictionally engaged over the edge of the center disc.
2. Related Prior Art
Conventional type blower wheels are typically constructed with a pair of disc shaped support plates formed with a conical shape and located in abutting relation with each other such that the outer edges of the plates are joined together and the central areas of the plates are in spaced relation to each other. Each plate includes a hub joined thereto whereby the plates are mounted to a common drive shaft. The plates and hubs define a center disc assembly which is driven in rotation by the common shaft. A blade assembly comprising a plurality of circumferentially spaced blades are arranged around and supported on the outer peripheral edge of the disc assembly. In a known construction, each of the blades is provided with a notch located centrally between either end of the blade and located at an inner edge of the blade. A peripheral edge of each of the plates is positioned in frictional engagement with an adjacent notch edge, and the frictional engagement between the center disc assembly and the blade notches define a connection between the blade assembly and the center disc assembly such that rotation of the center disc assembly causes rotation of the blade assembly. Examples of such blower wheel constructions are shown in U.S. Pat. Nos. 3,423,012 and 4,515,527.
While this construction has been used for a number of years with satisfactory results, there is an ongoing need for an improved connection between the center disc assembly and the blade assembly. In short, there is a need for the formation of a positive connection between the two assemblies for preventing slippage of the blade assembly relative to the disc assembly in response to torque applied to the drive shaft supporting the center disc assembly.